System.Xml.Xsl.XsltArgumentList.RemoveExtensionObject C# (CSharp) Method

        public object RemoveExtensionObject(string namespaceUri)
        {
            object extension = _extensions[namespaceUri];
            _extensions.Remove(namespaceUri);
            return extension;
        }

 public void RemoveExtObj5()
 {
     m_xsltArg = new XsltArgumentList();
     MyObject obj = new MyObject(5, _output);
     ///nonePermSet.PermitOnly(); ;
     m_xsltArg.AddExtensionObject("urn:" + szLongNS, obj);
     m_xsltArg.RemoveExtensionObject("urn:" + szLongNS);
     ///CodeAccessPermission.RevertPermitOnly();
     try
     {
         if ((LoadXSL("MyObjectDef.xsl") == 1))
             Transform_ArgList("fruits.xml", true);
     }
     catch (System.Xml.Xsl.XsltException)
     {
         return;
     }
     _output.WriteLine("Did not throw expected exception");
     Assert.True(false);
 }